Reigning American League Cy Young award winner Robbie Ray is finalizing a five-year deal worth $115 million with the Mariners, according to ESPN's Jeff Passan.
The contract includes an opt-out after the third season.
Ray, 30, led the AL in ERA (2.84), strikeouts (248), WHIP (1.05) and innings pitched (193.1), with a 13-7 record over 32 starts with Toronto last season.
He took home the league's top pitching honor after receiving 29 of 30 first-place votes.
His stellar performance came after Ray struggled in 2020, allowing a 6.62 ERA between stints with Arizona and Toronto and a 7.